The present invention relates to an ink-jet recording head, and more particularly to an ink-jet head formed compactly by using a thin-film deposition technology such as ion milling.
Conventionally, a wire-driving printer head has been widely used as a printer head. The wire-driving printer head performs printing by driving wires magnetically and pressing the wires against a platen with a paper sheet or an ink ribbon interposed therebetween. The wire-dot printer head, however, has many disadvantages such as large power consumption, noise generation, and low resolution, thus leaving much to be desired as a printer device.
Therefore, a printer employing an ink-jet recording head using piezoelectric elements or air bubbles generated by heat has been developed lately. The ink-jet recording head, which is driven noiselessly with low power consumption and achieves high resolution, has come to the front as a preferred printer device.
The ink-jet recording head basically includes nozzles, ink chambers, an ink supply system, an ink tank, and a pressure-generating part. In a printer using the ink-jet recording head, displacement generated in the pressure-generating part is transmitted to the ink chambers as pressure so that ink particles are sprayed from the nozzles, thereby recording characters or images on a recording medium such as a sheet of paper.
According to the conventional known method, a thin-plate piezoelectric element is attached to one side of the outer wall of an ink chamber as a pressure-generating part. By supplying a pulse-like voltage to the piezoelectric element, a composite plate formed of the piezoelectric element and the outer wall of the ink chamber deflects. Displacement generated by the deflection produces pressure that is applied to the ink chamber, so that ink is sprayed.
FIG. 1 is a schematic diagram showing an ink-jet recording head 10 and its periphery of a conventional printer 1, and FIG. 2 is a perspective view of the ink-jet recording head 10, showing the outline of a configuration thereof.
In FIG. 1, the ink-jet recording head 10 is attached to the lower surface of a carriage 2. The ink-jet recording head 10 is positioned between a feed roller 3 and an eject roller 4 so as to oppose a platen 5. The carriage 2 includes an ink tank 6, and is provided to be movable in a direction perpendicular to the surface of the FIG. 1 sheet. A paper sheet 7 is pinched between a pinch roller 8 and the feed roller 3 and further between a pinch roller 9 and the eject roller 4 to be conveyed in the direction indicated by the arrow A. The ink-jet recording head 10 is driven and the carriage 2 is moved in the direction perpendicular to the sheet surface so that the ink-jet recording head 10 performs printing on the paper sheet 7. The printed paper sheet 7 is stored in a stacker 20.
As shown in FIG. 2, the ink-jet recording head 10 includes piezoelectric elements 11, individual electrodes 12 formed on the piezoelectric elements 11, a nozzle plate 14 having nozzles 13 formed therein, metal or resin ink chamber walls 17 forming, with the nozzle plate 14, ink chambers 15 corresponding to the nozzles 13, and a diaphragm 16.
The nozzles 13 and the diaphragm 16 are positioned to oppose the ink chambers 15. The periphery of the ink chambers 15 and the corresponding periphery of the diaphragm 16 are firmly connected, and the piezoelectric elements 11 cause the respective corresponding parts of the diaphragm 16 to be displaced as indicated by the broken line in FIG. 2. Voltages are applied to the piezoelectric elements 11 by supplying electrical signals from the main body of the printer to the individual piezoelectric elements 11 through a printed board not shown in the drawing. The piezoelectric elements 11 supplied with the voltages contract or expand to cause pressure in the respective ink chambers 15 so that ink is sprayed. Thereby, printing is performed on the recording medium.
The piezoelectric elements 11 are formed on the above-described conventional ink-jet recording head 10 shown in FIG. 2 by attaching plate-like piezoelectric elements to positions corresponding to the ink chambers 15 or by-first attaching a piezoelectric element over the ink chambers 15 and then dividing the piezoelectric element according to the ink chambers 15.
If a thin piezoelectric element (smaller than 50 xcexcm) is employed in the thus produced conventional ink-jet recording head 10 in order to reduce the size thereof, a variation in the thickness of an adhesive agent used for the attachment causes variations in the displacement of the piezoelectric elements so that the characteristic of the ink head is deteriorated. Further, the piezoelectric element of this type has a problem in that a crack is made therein at the time of attachment.
Some inventors of the present invention, together with another inventor, have proposed a method of producing an ink-jet recording head using a thin-film deposition technology in order to eliminate the above-described disadvantage. However, there is still room for improvement in this method.
That is, a principal object of the present invention is to provide a highly accurate, downsized ink-jet recording head producible at low cost and a method of producing the same by making further improvements with respect to an ink-jet recording head produced by using a thin-film deposition technology.
The above object of the present invention is achieved by an ink-jet recording head in which a piezoelectric layer is formed subsequent to an electrode layer on a substrate by using a thin-film deposition technology and an energy-generating element for generating energy for ink ejection is formed by etching the electrode and the piezoelectric layers simultaneously by an ion milling process, the ink-jet recording head including a fine powder reception part on which mixed fine powders including at least those etched off the electrode layer and the piezoelectric layer by the ion milling process are deposited, the fine powder reception part being provided in a periphery of the energy-generating element.
In the present invention, an energy-generating element having integrality can be produced since the electrode layer and the piezoelectric layer are etched simultaneously by ion milling.
Further, a large area can be processed by etching by ion milling, and etching anisotropy is high in a vertical direction with respect to the processed surface. Accordingly, the shape of the energy-generating element can be designed freely, and its etched sections are vertical without any unnecessary taper parts formed thereon.
Mixed fine powders generated by the ion milling are deposited on a fine powder reception part. Therefore, the mixed fine powders are prevented from adhering to the important energy-generating element.
The mixed fine powders deposited on the fine powder reception part can be removed easily by the physical force of pressurized liquid or gas. Therefore, the removal process can be performed in a short period of time at low cost. Accordingly, a downsized ink-jet recording head having high accuracy and reliability can be provided at low cost.
Further, the fine powder reception part can be formed as an island-like member provided at a position 300 xcexcm or less apart from an end of the energy-generating element.
When there exists space including a length exceeding 300 xcexcm from the end of the energy-generating element, by providing the island-like member at a position 300 xcexcm or less apart from the end of the energy-generating element, the mixed fine powders can be deposited on the member. Therefore, the mixed fine powders are prevented from adhering to the important energy-generating element.
Further, the island-like member can be formed as an auxiliary frame body for reinforcing the ink-jet recording head. The auxiliary frame body performs not only the function of reinforcing the ink-jet recording head but also the function of preventing-the mixed fine powders from adhering to the energy-generating element.
Further, the island-like member or the auxiliary frame body can be formed at the same time that the electrode and piezoelectric layers are ion-milled. That is, this can be easily performed by changing a photoresist pattern used in forming the energy-generating element to a pattern that preserves the island-like member or the auxiliary frame body.
Further, the fine powder reception part can be formed as an annular groove provided around the energy-generating element so that the energy-generating element can be formed therein.
The mixed fine powders can be deposited on an outer wall surface inside the groove by simply providing the annular groove on which the mixed fine powders are to be formed. The groove is preferably 300 xcexcm or less in width.
The groove can be formed at the same time that the electrode and piezoelectric layers are ion-milled. That is, this can be easily performed by altering the photoresist pattern used in forming the energy-generating element.
Further, the above object of the present invention is also achieved by a method of producing an ink-jet recording head, the method including the steps of: forming a piezoelectric layer subsequent to an electrode layer on a substrate by using a thin-film deposition technology; forming an energy-generating element for generating energy for ink ejection by etching the electrode and the piezoelectric layers simultaneously by an ion milling process, and forming a fine powder reception part on which mixed fine powders including at least those etched off the electrode layer and the piezoelectric layer by the ion milling process are deposited, the fine powder reception part being provided in a periphery of the energy-generating element; and removing the fine powders deposited on the fine powder reception part.
By ion milling, the energy-generating element can be formed by etching the electrode and piezoelectric layers at the same time, and the fine powder reception part is formed simultaneously with the energy-generating element. The fine powders are deposited on the fine powder reception part. Therefore, the ink-jet recording head can be produced without the fine powders adhering to the energy-generating element. Further, the mixed fine powders formed on the fine powder reception part can be removed easily in the subsequent removal process.
The fine powder reception part can be formed simultaneously with the energy-generating element by altering the photoresist pattern. Accordingly, this can be performed easily by making a simple alteration to the photoresist pattern.
The fine powder reception part can be an island-like member provided at a position 300 xcexcm or less apart from the end of the energy-generating element.
The fine powder reception part can be an annular groove provided for forming the energy-generating element, the annular groove being 300 xcexcm or less in width.
The process for removing the mixed fine powders can be provided to physically remove the mixed fine powders by using pressurized liquid or gas. The mixed fine powders can be removed with simple facilities, so that the production cost can be reduced.
Further, another object of the present invention is to provide a printer including the above-described ink-jet recording head. Since the downsized, highly reliable ink-jet recording head produced at low cost is employed, the printer can be reduced in cost.